A wave of airline mergers has led to more rational pricing strategies by the big carriers. The days of huge fare wars seem to be over. That's great news for investors, even if it's bad news for travelers.

Many airlines have boosted revenue though by adding on higher fees and surcharges for things like checking bags and pre-printing boarding passes.

Still, there have been some concerns on Wall Street lately that the good times for the industry may soon be over. JetBlue and Alaska Air are the only two major airline stocks up this year.

The rest have fallen on fears that profit margins may be close to peaking. Fuel prices, while still down sharply, are up from their lows.

And the Department of Justice has accused Southwest, Delta, United and American of possibly colluding to keep capacity growth down. Doing so could keep fares higher than they otherwise would be.

There have been some calls for airlines to cut ticket prices because fuel costs have dropped so dramatically.

But Southwest said that its average ticket price dropped 3.4% from a year ago to $157.51.

United and Delta also both reported declines in a key airline metric known as passenger revenue which accounts for fares and fees. The strong dollar is partly to blame for this though, since it reduces the value of what foreign travelers pay to fly.

Still, the airline industry may be in a rare state of cruising altitude for both investors and passengers. Profits are climbing and consumers can still find some good bargains.